Capillary fiber dialyzers are currently being used in the dialysis of blood, and also show promise for use as oxygenators for blood and for other types of semi-permeable diffusion apparatus. An example of such a capillary fiber dialyzer is the CF.RTM. dialyzer sold by the Artificial Organs Division of Travenol Laboratories, Inc.
Other forms of capillary dialyzers involving a multiple tube flow path includes a Kohl U.S. Pat. No. 3,557,962, Riede U.S. Pat. No. 4,016,082, West German Patent Publication 2,824,898 of Cordis Dow Corporation, published on Dec. 21, 1978, and West German Pat. No. 2,622,684.
It has long been known to be desirable, particularly in blood dialysis as well as other diffusion techniques involving blood, for the blood flow paths to be of capillary nature, having a transverse dimension of, for example, 500 microns or less. These capillary flow paths for the blood or other material improve the dialysis efficiency of the device. Such capillary tubes are used, for example, in the commercial capillary fiber dialyzer mentioned above, as well as other commercial capillary fiber dialyzers.
It would be desirable to form joined arrays of capillary semi-permeable tubes, for example, to obtain an independent sheet of such joined capillary tubes. However, no efficient and effective way of manufacturing joined arrays of such tubes having a maximum transverse inner diameter of less than one millimeter has been available prior to this present invention.
In accordance with this invention, a diffusion membrane unit defining an internal flow path is provided in which joined tubes define individual flow channels through the diffusion membrane unit which may have a maximum transverse dimension of less than one millimeter or one thousand microns, with a minimum transverse dimension being as low as 70 or 100 microns, for greatly improved dialysis efficiency, or corresponding improvements in any other desired diffusion process.